The present invention relates to a linear-motion ball bearing assembly. Around the circumference of such bearing assemblies are continuous circulating ball races with balls under load being supported in the bore of a metallic supporting shell or sleeve and balls not under load being turned around at the ends of the shell and returned via the casing surface of the shell.
The prior art includes a ball bearing of this type, in which the balls under load are guided longitudinally in a transversely divided cage shell or sleeve consisting of two cage half sections, whereby the outer end of each half section of the cage is thickened radially for the purpose of taking up the guidance part, as shown in German Utility Pat. No. 7,014,919. This known ball bearing has the disadvantage that, in addition to the supporting shell, an exterior shell must be provided which includes in its bore the supporting shell and the two halves of the cage, which must be tightly held axially and radially in the bore. In addition, considerable manufacturing costs are associated with providing the opposite ends of the two halves of the cage with plug-in contact, so that the two halves of the cage are fixed to one another without being able to rotate, and an exactly aligned longitudinal guidance of the balls under load is ensured in the cage shell. Finally, the cage shell of the known ball bearing can easily have defects, if it is manufactured from an abrasion-resistant plastic which can be injection molded, as is desirable for manufacturing and functional reasons, because the halves of the cage have a significantly greater wall thickness at their outer thickened end than at their inner end. Accordingly, damaging heat tensions may result when the cage halves are injection molded, and shrinkage after injection molding may result in two different diameters between the outer and inner ends of the cage halves. These different diameters of the cage can also be caused by non-uniform heat expansion, if the ball bearing warms up as a result of friction during operation. All of this leads to a damaging distortion of the cage shell which is constructed of a plastic, e.g. a thermoplastic, and accordingly to an impairment of the efficiency of the known ball bearing.
An object of the present invention is to create an improved ball bearing of the above-described type, which has dimensional accuracy and a simple construction. In addition, it should be possible to manufacture the ball bearing with inexpensive means.